The region of ancient Cynuria coincides for the most part with the modern eparchy of Kynouria, which belongs to the Nomos of Arkadia. In trying to define the borders of ancient Cynuria with greater accuracy, account has been taken of the natural boundaries, especially the dividing lines of the rivers, in addition to the ancient literary evidence.

Cynuria is dominated by the Parnon mountain range (alt. 1934 m), which runs in a NW-SE direction. Like a great wall, it closes off Cynuria along the whole of its western side and acts as a barrier between the region of Cynuria and the neighbouring states of Sparta and Tegea. On the north the ridges of Mt Parthenion, commanded by the Zavitsa spur (alt. 974 m), separate Cynuria from the states of Argos and Tegea. The eastern side of Cynuria is washed by the waters of the Argolic gulf. Most of the coastline is made up of numerous bays and headlands. The bay of Thyrea can be identified as the modern bay of Astros. The geographical formation makes it possible to divide the district into two large units: the northern, comprising the districts of Astros, Ag. Andreas, Ag. Petros, Kastri, etc., corresponding to Thyreatis in ancient times, and the southern, including the districts of Tsakonia, Kounoupia, Kosmas, etc., corresponding to the region around Prasiai or Brasiai.

Three mountain torrents have their origins on the slopes of Parnon and run down to the Argolic gulf. They are the Tanos in the north, the Vrasiatis further south, and the Daphnon to the south in the district of Leonidion. The Tanos is identified with the river of the same name mentioned by Pausanias. Most of the year these riverbeds contain no water, but at times they become raging torrents and flood the plains below, depositing a layer of silt that enriches the soil and makes it fertile.